Elongated items such as wiring bundles or optical cable used for communications networks, power transmission and the like are often installed in protective ducts which may be buried underground, strung from support stanchions or positioned within building structures along with other utility and service lines. Such ducts are often flexible extruded polymer tubes which provide substantially continuous protection to the elongated items from moisture, abrasion, impact and other environmental hazards.
It is found advantageous to ensheath the elongated items within flexible protective sleeves that are pre-positioned within the ducts. Protective sleeves help separate the various items from one another within a duct and organize them to obtain increased efficiency of use of the limited duct space. The sleeves also protect the elongated items from abrasion caused when additional elongated items are drawn through ducts already populated by other elongated items.
The sleeves are preferably woven from tough polymer monofilaments allowing them to withstand relatively high tensile forces encountered when they are drawn through the ducts over lengths of a mile or longer. Several such protective sleeves are preferably installed in a duct. To conserve space within the duct, and also to facilitate drawing of the sleeve through it, the sleeves are installed in a flat or collapsed configuration. The sleeves are flexible however, and expand outwardly to accommodate the elongated items drawn through them. Each sleeve initially has a high strength pull tape within it. When it is desired to install an elongated item within the duct, the item is attached to one end of a pull tape of one of the sleeves and the pull tape is drawn through the sleeve (the sleeve being held within the duct), drawing the item with it.
In view of the significant lengths that ducts may reach, it is necessary to have the capability of splicing the protective sleeving end to end to ensure that the length of the sleeving exceeds the length of the duct. It is desirable that the splice have a tensile strength equal to or greater than the tensile strength of the sleeve itself to avoid the splice forming a weak link where the sleeve might tend to separate when subjected to tensile force during a pull through a duct. Alternately, the splice should have a tensile strength that exceeds the tension experienced by the sleeve during a pull through a duct. In any event, the splice must not inhibit the ability of the sleeve to expand and accommodate an elongated item, nor should it inhibit the motion of the pull tape through the sleeve.